package com.neusoft.elm.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBUtil {

	private static final String URL="jdbc:mysql://localhost:3306/elm?characterEncoding=utf-8";
	private static final String DRIVER="com.mysql.jdbc.Driver";
	private static final String USERNAME="root";
	private static final String PASSWORD="123456";
	
	private static final ThreadLocal<Connection>TL=new ThreadLocal<>();
	
	//获取Connection
	public static Connection getConnection() {
		Connection con=null;
		con=TL.get();
		if(con==null) {
			con=createConnection();
			TL.set(con);
		}
		return con;
	}
	
	//开启一个事务
	public static void beginTransaction() throws Exception{
		Connection con=null;
		con=TL.get();
		if(con==null) {
			con=createConnection();
			TL.set(con);
		}
		con.setAutoCommit(false);
	}
	
	//提交一个事务
	public static void commitTransaction() throws Exception{
		Connection con=TL.get();
		con.commit();
	}
	
	//回滚一个事务
	public static void rollbackTransaction() throws Exception{
		Connection con=TL.get();
		con.rollback();
	}
	
	//关闭资源
	public static void close(ResultSet rs,PreparedStatement pst) {
		try {
			if(rs!=null) {
				rs.close();
			}
			if(pst!=null) {
				pst.close();
			}
		}catch(SQLException e) {
			e.printStackTrace();
		}
		
	}
	
	public static void close(PreparedStatement pst) {
		try {
			if(pst != null) {
				pst.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	public static void close() {
		Connection con = TL.get();
		try {
			if(con != null) {
				con.close();
			}
			//必须要remove，否则会造成内存泄露问题.
			TL.remove();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	
	
	
	private static Connection createConnection() {
		Connection con=null;
		if(con==null) {
			try {
				Class.forName(DRIVER);
				con=DriverManager.getConnection(URL,USERNAME,PASSWORD);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}	
		}
		return con;
	}
}
